Moondark for June: What's Up for Summer?

I’m just getting caught up after being away for a long weekend. So what’s up—in the news, in our sky, and ahead for this summer? “High fives!” for the Atlantis astronauts: they have just bid farewell to the overhauled Hubble Space Telescope. My news reader was stuffed with headlines marking the progress of the five space walks as well as some frustrations in revitalizing Hubble for at least five more years of cutting edge science and stunning photos. So when will the refurbished space telescope be visible in our sky? Check out Heavens Above's and Space Weather’s online pass predictors. In other space exploration news: the Mars rover Spirit has five wheels stuck in a ferric-sulfate salt sand. So far, 2009 has been a challenging year, with memory glitches and dusty solar panels. On the other side of the Red Planet, Opportunity rolls onward toward Endeavour Crater. And last week, the ESA launched two space telescopes. The Herschel Space Observatory’s 3.5-m diameter primary mirror is the largest ever sent into space and is designed for the study of newly forming stars and galaxies at far infrared wavelengths not available to ground-based telescopes. Planck Surveyor is a microwave telescope that will scan the whole sky to map the cosmic background radiation at parts per million levels. The polarization of the CMB photons will also be measured to shed light on inflation of the early universe. Both telescopes are on their way to the L2 point 1.5 million miles from the us directly opposite the Sun. To avoid swamping their sensitive detectors, both telescopes must be located far away from radiation emitted by Earth. Much closer to home and as close as the Delaware Bay shoreline, it’s time for the annual spawning of the horseshoe crabs. This too is an astronomical phenomenon: spawning and egg laying are precisely timed to the spring tides of early summer. You’ll find the nesting horseshoe crabs, as well as volunteers counting them, on the nocturnal high tides around the full moon on June 7th and new moon on the 22nd. Both hurricane season and meteorological summer begin on the first of June. Astronomically, the summer starts on the solstice as the Sun (eerily quiet so far this year) reaches its northernmost point in the sky on June 21st in the middle of our night, 01:45 EDT to be precise. Earth is farthest from the Sun, just over 152 x 106 kilometers on July 3rd. And we miss all three eclipses this summer: two slight penumbral lunar eclipses on either side of the longest total solar eclipse of the century on July 22nd; India, China and the western Pacific Ocean are favored locations. For the early summer, Saturn is the only bright planet visible, easy to find as soon as night falls, located below Leo’s hindquarters. But this planet’s most distinguishing figure, its rings are shrinking and will all but disappear as summer closes. Ring-plane crossing is on September 4th, just ahead of its conjunction with the Sun on the 17th. Jupiter reaches opposition in mid August and is brilliant and visible all night long. How many of you will try again for the Perseid meteor shower? The moon is near last quarter, but the meteor-optimists project greater than average activity. For my part, I’m afraid the spectacular displays a decade ago have spoiled me forever. Instead, how about a nice summertime comet, like Hyakutake in 1996? Summer is a time to relax, put up your feet and enjoy the warm evenings under the Milky Way. Let the mind wander and wonder about the infinitesimal difference in refraction of light, red a bit less and blue slightly more, that creates a rainbow following a thundershower. Dispersion also accounts for the green flash and colors of twinkling stars. Ponder why the sky is blue? Or why are there no green stars? Or consider the near coincidence of moon and sun’s angular size, one-half a degree, leading to rare and spectacular eclipses and comparable tidal effects, spring tides and neap tides, on the sea as well. And don’t forget the bug spray. Summer comes to a close with the No Frill Star Party followed immediately by the equinox on September 22. It’s just thirteen weeks long, only 93.65 days. How did you spend your 2009 summer vacation? Moondark is written by Douglas C. Miller, published at the Moondark web site, and printed in the Delmarva Star Gazers' Star Gazer News. This document was last revised on 21 May 2009. Text and graphics on this web page are free for non-commercial use with attribution under a Creative Commons Attribution-Non-commercial 3.0 License. Ask Doug about other uses.